• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.665-670
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• 2016

Prevailing dissemination of machine tools and cutting technology have caused drastic developments of high speed dry machining with work materials of high hardness, and demands on the high-hardness-materials with high efficiency have become increasingly important in terms of productivity, cost reduction, as well as environment-friendly issue. Addition of Si to TiAlN has been known to form nano-composite coating with higher hardness of over 30 GPa and oxidation temperature over $1,000^{\circ}C$. However, it is not easy to add Si to TiAlN by using conventional PVD technologies. Therefore, Ti-Al-Si-N have been prepared by hybrid process of PVD with multiple target sources or PVD combined with PECVD of Si source gas. In this study, a single composite target of Ti-Al-Si was prepared by powder metallurgy of MA (mechanical alloying) and SPS (spark plasma sintering). Properties of he resulting alloying targets were examined. They revealed a microstructure with micro-sized grain of about $1{\sim}5{\mu}m$, and all the elements were distributed homogeneously in the alloying target. Hardness of the Ti-Al-Si-N target was about 1,127 Hv. Thin films of Ti-Al-Si-N were prepared by unbalanced magnetron sputtering method by using the home-made Ti-Al-Si alloying target. Composition of the resulting thin film of Ti-Al-Si-N was almost the same with that of the target. The thin film of Ti-Al-Si-N showed a hardness of 35 GPa and friction coefficient of 0.66.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.5
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• pp.267-274
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• 2009

Titanium Chromium Nitrided (TiCrN) coatings were deposited on stainless steel 316 L and Si (100) wafer by inductively coupled plasma assisted D.C. magnetron sputtering at the various sputtering power on Cr target and $N_2/Ar$ gas ratio. Increasing the sputtering power of Cr target, XRD patterns were changed from TiCrN to nitride $Cr_2Ti$. The maximum hardness was $Hk_{3g}$ 3900 at $0.3\;N_2/Ar$ gas ratio. The thickness of the TiCrN films increased as the Cr target power increased, and it showed over $Hk_{5g}3100$ hardness at 100 W, 150 W. TiCrN films were deposited by the ICP assisted DC magnetron sputtering shown good wear resistance as the $N_2/Ar$ gas ratio was 0.1, 0.3.

• Korean Journal of Crystallography
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• v.11 no.2
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• pp.95-101
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• 2000

Ferroelectric SrBi2Ta2O9 (SBT) thin films of Pt/Ti/SiO2 electrode were fabricated using a sintered SBT target with various Bi2O3 content by rf magnetron sputtering. Good hysteresis loop characteristics were observed in the SBT thin films deposited with 50mol% excess Bi target. SBT thin films crystallized from 650℃ however, good hysteresis loop can be obtained in the film annealed above 700℃. pt/TiO2/SiO2 and Pt/SiO2 electrodes were also used to investigate the Pt electrode dependence of SBT thin films. SBT thin films showed random oriented polycrystalline structure and similar morphology regardless of electrodes with quite different surface morphology. A 0.2㎛ thick SBT film annealed at 750℃ exhibited the remanent polarization (2Pr) of μC/㎠ and coercive voltage(Vc) of 1V at an applied voltage of 5V.

• Korean Journal of Materials Research
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• v.26 no.12
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• pp.676-680
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• 2016

We have investigated the properties of thin film transistors(TFT) fabricated using zinc tin oxide(ZTO) thin films deposited via on-axis sputtering and FTS methods. ZTO thin films deposited by FTS showed lower root-mean-square(RMS) roughness and more uniformity than those deposited via on-axis sputtering. We observed enhanced electrical properties of ZTO TFT deposited via FTS. The ZTO films were deposited at room temperature via on-axis sputtering and FTS. The as-deposited ZTO films were annealed at $400^{\circ}C$. The TFT using the ZTO films deposited via FTS process exhibited a high mobility of $12.91cm^2/V.s$, a low swing of 0.80 V/decade, $V_{th}$ of 5.78 V, and a high $I_{on/off}$ ratio of $2.52{\times}10^6$.

• Journal of electromagnetic engineering and science
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• v.11 no.1
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• pp.1-4
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• 2011

In this letter, we propose a novel tag antenna that has low performance degradation with nearby dielectric material. We obtained a stable reading performance and a broad matching bandwidth on nearby dielectric materials by employing a T-matching network with thick line width and capacitively slot-loaded arms. We then built the proposed antenna and measured the tag sensitivity to examine the reading characteristics with nearby dielectric materials. The measured results clearly demonstrate stable tag sensitivity with various nearby dielectric materials, such as foam, acrylic-plastic, glass, and ceramic plates. To more closely observe the antenna characteristics with nearby dielectric materials, we also examined the impedance variation and surface current distribution with respect to the dielectric constant of nearby target objects, which ranged from $1{\times}{\varepsilon}_0$ to $16{\times}{\varepsilon}_0$.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.509-514
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• 2011

In this study, optical emission spectroscopy was used to monitor the plasma produced during the RF magnetron sputtering of a $BaTiO_3$ target. The intensities of chemical species were measured by real time monitoring with various discharge parameters such as RF power, pressure, and discharge gas. The emission lines of elemental and ionized species from $BaTiO_3$ and Ti targets were analyzed to evaluate the film composition and the optimized growth conditions for $BaTiO_3$ films. The emissions from Ar(I, II), Ba(I, II) and Ti(I) were found during sputtering of the $BaTiO_3$ target in Ar atmosphere. With increasing RF power, all the line intensities increased because the electron density increased with increasing RF power. When the Ar pressure increased, the Ba(II) and Ti(I) line intensity increased, but the $Ar^+$ line intensity decreased with increasing pressure. This result shows that high pressure is of greater benefit for the ionization of Ba than for that of Ar. Oxygen depressed the intensity of the plasma more than Ar did. When the Ar/$O_2$ ratio decreased, the intensity of Ba decreased more sharply than that of Ti. This result indicates that the plasma composition strongly depends on the discharge gas atmosphere. When the oxygen increased, the Ba/Ti ratio and the thickness of the films decreased. The emission spectra showed consistent variation with applied power to the Ti target during co-sputtering of the $BaTiO_3$ and Ti targets. The co-sputtered films showed a Ba/Ti ratio of 1.05 to 0.73 with applied power to the Ti target. The films with different Ba/Ti ratios showed changes in grain size. Ti excess films annealed at $600^{\circ}C$ did not show the second phase such as $BaTi_2O_5$ and $TiO_2$.

• Korean Journal of Metals and Materials
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• v.49 no.11
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• pp.845-852
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• 2011

The Spark Plasma Sintering(SPS) method offers a means of fabricating a sintered-body having high density without grain growth through short sintering time and a one-step process. A titanium compact having high density and purity was fabricated by the SPS process. It can be used to fabricate a Ti sputtering target with controlled parameters such as sintering temperature, heating rate, and pressure to establish the optimized processing conditions. The compact/target(?) has a diameter of ${\Phi}150{\times}6.35mm$. The density, purity, phase transformation, and microstructure of the Ti compact were analyzed by Archimedes, ICP, XRD and FE-SEM. A Ti thin-film fabricated on a $Si/SiO_2$ substrate by a sputtering device (SRN-100) was analyzed by XRD, TEM, and SIMS. Density and grain size were up to 99% and below $40{\mu}m$, respectively. The specific resistivity of the optimized Ti target was $8.63{\times}10^{-6}{\Omega}{\cdot}cm$.

• Transactions on Electrical and Electronic Materials
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• v.14 no.4
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• pp.187-192
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• 2013

Because of the importance of small target detection in infrared images, many studies have been carried out in this area. Using a Kalman filter and mean shift algorithm, this study proposes an algorithm to track multiple small moving targets even in cases of target disappearance and appearance in serial infrared images in an environment with many noises. Difference images, which highlight the background images estimated with a background estimation filter from the original images, have a relatively very bright value, which becomes a candidate target area. Multiple target tracking consists of a Kalman filter section (target position prediction) and candidate target classification section (target selection). The system removes error detection from the detection results of candidate targets in still images and associates targets in serial images. The final target detection locations were revised with the mean shift algorithm to have comparatively low tracking location errors and allow for continuous tracking with standard model updating. In the experiment with actual marine infrared serial images, the proposed system was compared with the Kalman filter method and mean shift algorithm. As a result, the proposed system recorded the lowest tracking location errors and ensured stable tracking with no tracking location diffusion.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.106-109
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• 2012

Purpose : The KOTRON-13 cyclotron was developed and installed in regional cyclotron centers to produce short-lifetime medical radioisotopes. However, this cyclotron has limited capacity to produce $^{11}C$ so far. In present study, we developed an effective $^{11}C$ target system combining with fluorine-18 target and applied to the production of various $^{11}C$ radiopharmaceuticals. Materials and Methods : To develop the optimal $^{11}C$ target system and effective its cooling system, we designed the $^{11}C$ target system by Stopping and Range of Ions in Matter (SRIM) simulation program and considered the cavity pressure during irradiation at target grid. In this investigation, we modified target materials, cavity shapes and the position of cooling system in $^{11}C$ target and then evaluated $[^{11}C]CO_2$ production at different beam currents, thickness of the target foil, oxygen content of nitrogen gas and target gas loading pressure. Also, we evaluate the production of several $^{11}C$ radiopharmaceuticals such as [$^{11}C$]PIB, [$^{11}C$]DASB, and [$^{11}C$]Clozapine. Results : $[^{11}C]CO_2$ was produced about 74 GBq for 30min irradiation at 60 ${\mu}A$ of beam current as following conditions: thickness of the target foil: 19 nm HAVAR, oxygen content of nitrogen: under 50 ppb, target gas loading pressure: 24 bar. Additionally, the cooling system was stable to produce $[^{11}C]CO_2$ at high beam current. The radiochemical yields of [$^{11}C$]PIB, [$^{11}C$]DASB, and [$^{11}C$]Clozapine showed about 26-38% with over 127 GBq/umol of specific activity. Conclusion : The carbon-11 target system in the KOTRON-13 cyclotron was successfully developed and showed stable production of $[^{11}C]CO_2$. These results showed that our $^{11}C$ target system will be compatible with other commercial system for the routine $^{11}C$ radiopharmaceuticals production in the KOTRON-13 cyclotron.

• Electrical & Electronic Materials
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• v.9 no.5
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• pp.490-497
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• 1996

RF마그네트론 스파터링에 의한 $sSnO_2$ 박막을 증착한 결과 작동조건에 따라 표면에서 막손상이 발생하였는데, 이는 target에서 생성된 높은 에너지의 고속입자가 기판에서 직접 충돌로 일어나며, 마그네트론의 자계분포와도 관계된다. 또한 기판의 위치에 따라 박막의 전기적, 구조적 특성이 급격히 변하는데 본 논문은 중심자석의 세기와 RF power, 가스압력, 그리고 기판온도 등의 스파터링 작동조건을 변화시키면서 박막의 비손상을 검토하였고, 물성특성을 평가하였다. 실험결과로 부터 기판의 외축부에서 제작된 박막은 전반적으로 막손상이 없었고, 특히 target의 중심자석을 Cobalt로 설치하고 15 mTorr의 가스압력과 50 W의 RF power로 한 경우 가장 우수한 특성을 가진 박막을 얻을 수 있었다. 추가로 막손상을 방지하고자, 환원형의 masking glass를 target위에 설치하였는데, 고에너지 입자의 직접 충돌을 확실히 차단할 수 있었으며, 비저항율도 target의 부식부위 (erosion)에 대응하는 부분에서 100배 정도로 개선하였다.